I just picked up my first f150 and im having a little trouble with a hard knock. heres some background information on her... she sat for 3 years with no run time in a driveway until i came along and bought her. before trying to start the engine i gave her fresh oil with half a can of seafoam, pumped the gas tanks dry and put fresh fuel in, changed the fuel filter, and put in a fresh battery. she started up with just a lil trouble from the starter soilenoid and some light noise from the lifters that cleared about to weeks later. shortly after i put new plugs, wires, cap, and rotor in. i've done about 4 oil changes this month and i've gotten most of the sludge out of the engine. she was running great until the other day when i started getting a very loud knock from the engine. it almost sounds like a cylinder isnt firing. i checked the connections to the plugs and put a msd coil in with no effect. anybody have any suggestions?

 

First I would determine if its a cylinder not firing or a mechanical fault. If a cylinder isn't firing the spark plug will be wet. Pulling the plug wire from the cylinder that has a bad rod bearing will reduce the noise. A timing light can be used to find the bad cylinder too.
regards
rikard

 

After about 2 weeks of troubleshooting, me and my mechanics have concluded what i didnt want to hear.... rod bearings. I've been doing some research and i'm pretty sure that I can change the bearings without pulling the engine. I'm going to need to bar the engine over to access each of the bearings and I was wondering if anybody had and tips/precautions before i start this job

 

You'd probably be wasting your time trying to replace the bearings without pulling the engine. Usually when a rod bearing starts knocking badly it messes up that crankshaft journal and very likely that connecting rod. To properly fix the engine you would need to remove the engine from the vehicle remove the crankshaft, take the crankshaft to a good engine shop and have all the rod and main bearing journals miked, and take the connecting rod(s) and have the shop check them out. Thers's a lot more to it than that, but that's a start.

 

Nothing against the Original Poster, as literally millions of people refer to their motor vehicles as female, but am I the only person whose skin crawls when they read/here this figure of speech? I know ships are referred to as "she" and I have less of a problem with that, but there is nothing femine about an F-250 H.D., nor any modern F-series, IMNSHO. In fact, the whole idea of anthropormorphizing inanimate objects kind of skeeves me....

But I do wish the O.P. good luck--perhaps he can find a good, used engine to swap in? And actually, hold on, Jeffrey--you might want to post what diagnostics were done by your mechanics, just to see if the Brain Trust here agrees with their diagnosis, before you give up on this engine.

Did anyone put a stethascope on it? What were the results of disconnecting the plug wire--did the knock get less audible, as was discussed here?

Do we even know what engine you have in it? How many miles? What kind of service history?

 

you find me a dude with as many mood swings as my truck and i'll call it a him.

 

Some info on the truck...
110k miles
sat for 3 years without starting prior to me buying
checked all plugs... all have strong spark
fuel systems checks out ok
its not the lifters
oil level is normal and a nice honey color

I'm pretty sure the bearings wernt getting enough oil from the pump.... pumps output pressure was on the low side.

i've been look'n at higher capacity oil pumps... any suggestions... some say you have to modify the oil pan...

 

don't rig it with an oil pump if it were my engine i would rebuild it .030 over with some forged pistons and see how bad the crank and rods are if they are too bad get a stroker kit, it's just a little more expensive than getting new crank and rods, keep the stock stuff on top till you get the money to upgrade it but you'll know you'll always have a rock solid bottom end

and this is all if it's not a 6cyl.